Preliminary cooling of continuous casting machine

ABSTRACT

Cooling a continuous casting machine during the preliminary stages of casting molten metal, in which coolant is sprayed at a relatively low velocity onto the external surfaces of the flexible band and casting wheel which form the mold into which the molten metal is poured. The coolant is applied at the relatively low velocity prior to and during the initial pouring of the molten metal, and when the operator of the casting machine has established a proper constant level of molten metal in the mold and the hazard of splashing and explosion of the molten metal has been reduced, the coolant is applied at increased velocities and volumes and the rate of casting the molten metal is increased.

United States Patent PRELIMINARY COOLING OF CONTINUOUS CASTING MACHINE 4Claims, 4 Drawing Figs.

U.S. Cl. 164/87, 164/1 26 Int. Cl. B221! 11/06 Field of Search 164/4,122,

[56] References Cited UNITED STATES PATENTS 3,333,629 8/1967 Ward[64/283 X Primary Examiner-R. Spencer Annear Attorney-Jones & ThomasABSTRACT: Cooling a continuous casting machine during the preliminarystages of casting molten metal, in which coolant is sprayed at arelatively low velocity onto the external surfaces of the flexible bandand casting wheel which form the mold into which the molten metal ispoured. The coolant is applied at the relatively low velocity prior toand during the initial pouring of the molten metal, and when theoperator of the casting machine has established a proper constant levelof molten metal in the mold and the hazard of splashing and explosion ofthe molten metal has been reduced, the coolant is applied at increasedvelocities and volumes and the rate of casting the molten metal isincreased.

Patented Aug. 3, 1971 2 Sheets-Sheet 1 Fl(3.l

ATTOR N EYS Patented Aug. 3, 1971 I 3,596,702

2 Sheets-Sheet 2 M i ii I 1 I I 1 1 I; l 'I I l 1 1' I l 1 I II I 1| If/28 j l O O Q5. l: 5 0 IE 0 g INVENTORS GEORGE C. WARD ll GEORGE E.LENAEUS ATTORNEYS PRELIMINARY COOLING OF CONTINUOUS CASTING MACHINEBACKGROUND OF THE INVENTION In a casting machine which includes arotatable casting wheel defining a peripheral groove and a continuousflexible band which is applied to the groove and moves with the castingwheel throughout a substantial arc of its rotation to form an arcuatemoving mold, liquid coolant such as water is usually applied to theexternal surfaces of the mold as the molten metal is solidified. Theapplication of the coolant to the external surfaces of the moldincreases the heat transfer from the molten metal and the rate ofsolidification of the metal, and protects the mold from heatdeterioration. The casting wheel and flexible band are most vulnerablein the portion of the arcuate mold where the molten metal is poured intothe mold, since the molten metal is hottest at this point and thecasting wheel and band are heated from a relatively cool temperature toan extremely hot temperature and expand abruptly.

when the operator of a continuous casting machine initially sets themachine in operation, he usually causes the casting wheel to rotateslowly and flows the molten metal into the mold cavity at a relativelyhigh rate of flow until a pool of molten metal is formed, and he thenadjusts the rate of flow of molten metal and increases the rotationalspeed of the casting wheel while maintaining the pool of molten metal.The usual time lapse between initial pouring of molten metal into thearcuate mold formed by the casting wheel and flexible band and theapplication of the liquid coolant to the external surfaces of thearcuate mold is approximately seconds. During the initial pouring of themolten metal into the arcuate mold the casting wheel and the flexibleband are usually cooler than they are after the apparatus has been runfor a period of time since the apparatus initially retains a substantialamount of its residual room temperature, and the molten metal willinitially solidify in the arcuate mold without the necessity of theapplication of liquid coolant; however, the shock of the heat transferfrom the molten metal to the material of the relatively cool castingwheel and flexible band is significant and causes substantialdeterioration of these materials that would not occur if the moldsurfaces were continuously cooled during startup.

During this startup procedure there is a substantial hazard that thepool of molten metal will be improperly controlled and overflow themold. if molten metal contacts the coolant a violent explosion willresult. Thus, the operator of the casting machine usually establishedthe pool of molten metal in the arcuate mold before he causes thecoolant to be applied to the external surfaces of the casting wheel andflexible band, and carefully avoids overflowing the mold, in spite ofthe damage caused to the casting wheel and band due to the delay in applying the coolant.

SUMMARY OF THE INVENTION Briefly described, the present inventioncomprises a method and apparatus for cooling a continuous castingmachine wherein liquid coolant is applied before and during thepreliminary operation of the casting machine without any sub= stantialhazard of explosion due to the overflow of molten metal from the castingmachine or wet mold surfaces. The liquid coolant is applied to theflexible band and casting wheel at positions about the external surfacesof the arcuate mold where the likelihood of the coolant contacting theinternal mold surfaces prior to the initial pouring of the molten metalis remote, and where any overflowing molten metal is not likely tocontact the liquid coolant. The coolant is applied to the flexible bandat a low volume and velocity by means of a nip nozzle assemblypositioned between the band positioning roller and the band, and by theband header positioned im mediately adjacent the nip nozzle, and by thefirst stage wheel headers. While the application of the coolant is at alow volume and velocity, it is effective together with the residual roomtemperature of the casting wheel and flexible band to protect theseelements from heat deterioration during the initial pouring of moltenmetal, and for a span of time sufficient for the average metal castingmachine operator to establish the pool of molten metal in the a arcuatemold and to begin to bring the casting machine up to operational speed.

Thus, it is an object of this invention to provide a method andapparatus for cooling a continuous casting machine prior to and duringthe preliminary stages of casting metal substantially without anyhazards of explosion due to the inadvertent mixing of the coolant withthe molten metal.

Another object of this invention is to provide a preliminary coolingsystem for a continuous casting machine which functions to protect thecasting wheel and flexible band from inadvertent metal fatigue anddeterioration during the initial operation of the machine.

Another object of this invention is to provide a method of cooling acontinuous casting machine wherein the operator can operate the machinefor an extended period of time during the initial operation of themachine without the use of the main cooling system and without danger ofoverheating the machine.

Other objects, features and advantages of the present invention willbecome apparent upon reading the following specification, when taken inconjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side elevational view of acontinuous casting machine, with some parts eliminated for clarity.

FIG. 2 is a detailed showing of the portion of the casting machine ofFIG. 1 where the flexible band initially makes contact with theperipheral groove of the casting wheel.

FIG. 3 is a cross-sectional view of the casting wheel and its coolingheaders, taken along lines 3-3 of FIG. 2.

FIG. 4 is a front view of the nip nozzle and the upper portion of theupper band header, taken along lines 4 4 of FlG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in more detail tothe drawing, in which like numerals indicate like parts throughout theseveral views. FIG. 1 shows casting machine l0 which includes castingwheel 1]., continuous flexible band 12, and band positioning rollers14a, 14b, idc and 14d. As is shown in FIG. 3, casting wheel 11 comprisesan assembly which includes a rotatable support plate 15, positioningrims 16 and i8, and mold ring 19. Mold ring 19 defines outwardly facingannular peripheral groove 20 which includes inner wall 21 and slopingsidewalls 22. Gem tinuous flexible hand 12 closes peripheral groove 20to form an arcuate mold cavity which extends about the lower portion ofcasting wheel 1.1.

As is best shown in FIG. 2, band positioning roller 14a functions tomove continuous band 12 into contact with mold ring l9, and pouringspout 24 extends into the semicircular mold formed by band 12 and moldring 19. Pouring spout 24 functions to pour or deposit molten metal intothe semicircular mold from pouring pot 25 (FIG. 1), so that a pool ofmolten metal is formed. The rate of flow of molten metal from pouringpct 25 through pouring spout 24 is regulated so that he upper level 26of the pool of molten metal normally covers the lower end of pouringspout 24 to reduce the turbulence of the molten metal in thesemicircular mold.

Band positioning roller 14a defines a pair of annular grooves 28 and 29(FIG. 4). and nip nozzle assembly 30 is positioned closely adjacent baudpositioning roller 14a and projects into grooves 28 and 29. Nip nozzleassembly 30 is of the type disclosed in U.S. Pat. No. 3,333,629 andincludes a supply cut 31 and a pair of spaced wedge shaped nozzles 32and 33 which project into annular grooves 28 and 29, respectively.Supply duct 31 defines openings 34 within nozzles 32 and 33. Nozzles 32and 33 each includes a nozzle face plate 35 which is formed with acurvature matching the curvature of the outside surface of the mold ring19, anda plurality of nozzle openings 36 extend through nozzle faceplate35;"Nozzle openings 36 are formed so that they are directed generally ina downward direction from band positioning roller 14a, and the coolantpassing through nozzle openings 36 will flowp'rimarily only in adownward direction. The upper ends of the nozzle face plate 35 arepositioned as high within annular grooves 28 and 29 of band positioningroller l4a as practicaijandthe upper wall 38 of nozzles 32 and 33 isformed with 'acurvature generally matching the inner surface 39 ofgrooves zssnuzc.

Upper band header 40 is positioned immediately adja'cent and below nipnozzle assembly 30 and extends'in a downward direction around castingwheel 11. Lower band'header 41 (P16. 1) is positioned immediatelyadjacent andbelow'upper band header 40 and extends further in a downwarddirection and it terminates generally below casting wheel] 1. Rear bandheader 42 extends from the bottom portion of casting wheel 11 up towardband positioning roller 14d, and rear nip nozzle assembly 44 projectsbetween bind positioning roller 14d and casting wheel 11, in a mannersimilar to the projection of nip nozzle assembly 30 between bindpositioning roller l4aand casting wheel 11. I

A pair of side headers 45 are positioned on opposite sides of thearcuate mold and extend from the entrance of the arcuate mold down tothe bottom portion of casting wheel" ll, and similar side headers 46extends from the bottom of the casting wheel 1 1 up toward the exitportion of the arcuate mold.

Casting wheel headers 48. 49, and 50 are positioned adjacent rotatablesupport plate 15, generally in the same plane as mold ring 19. Castingwheel headers 48-50 each-extend through an arc of approximately 90 aboutcasting wheel 11, from hand positioning roller 14a, through the lowerportion of the casting wheel, up to band positioning roller 14d.Aplurality of nozzles 51 extend from the outer curved portion'oi.casting wheel headers 48-40, and function to spray coolant upon theinner surface 52 ofmold ring 19. i

As is shown in FIG. 1, the liquid coolant. suchas water, is carried tothe nip nozzles and headers of casting machine by means of main conduit52. A plurality of branch conduits extend from main conduit 52 andcommunicate .with the various nip nozzle assemblies and headers. Branchconduit 54 communicates with nip nozzle assembly 30, branch conduitSScommunicates with upper band header 40, branch conduit 56 communicateswith lower band header 41, branch conduit 57 communicates with the rearband header 42. branch conduits 58 and 59 communicate with side headers45, and branch conduits 60 and 61 communicate with side headers 46. Eachbranch conduit includes a manual control valve which functions toregulate the flow of coolant from mainconduit 52. Branch conduit 62extends from main conduit 52 and is connected to center valve connection64 of casting'whecl headers 48-50. Valve connection 64 includescontrolvalves 65. 66, and 67 which function to control the flow of. coolantfrombranch conduit 62 into each of casting wheel hoaders lfl eli,respectively. I J k k g Main control valve 70 is positionod'infmainconduit 52 and functions to control the flow of coolant through mainconduit 52 toward branch conduits 54-62. Main control gvalvo70 ispneumatically controlled, and the flow of actuating fluid to pneumaticcontrol motor 71 is governed by solenoid-actuated valve72.

Main bypass conduit 73 is connected to main conduitjSZ up= stream ofmain control valve 70. and bypass conduits. 75 and 76 communicatebetween main bypass conduits and branch conduits 54, 55, and withcasting wheel hcadcrs tti. respectively. The openings of bypass conduits74, 75, and 76 are also controlled by manual control valves.Checkyalvo's'78 and 79 are positioned in branch conduits 54 and 55upstream of the connections made between these conduitsa'nd theirrespective bypass conduits 74 and 75. Similarly. a'chcck valve (notshown) is located in valve connection 64'to prevent the flow of coolantfrom casting wheel header 48 back through valve connection 64 and branchconduit 62. The flow of coolant through main bypass conduit 73 iscontrolled by solenoidactuated valve 80! OPERATlON When the operator isto begin the continuous casting of metal in casting machine 10, he goesthrough the usual startup procedures, which include heating the metal inthe furnace to a temperature of over 2,000" Fahrenheit, preheating thelaunder and the pour pot, adjusting the band tension, drying the bandand wheel to assure that no moisture is present on these surfaces, andthe various other preliminary operations. Valve 80 of main bypassconduit 73 is opened so that liquid coolant is supplied through mainbypass conduit 73 to bypass conduits 74, 75, and 76. The manual valvesof branch bypass conduits 74-76 are preadjusted so that a low velocityand volume of coolant is supplied to nip nozzle assembly 30, upper bandheader 40, and casting wheel header 48. The coolant emerges from thenozzles connected to these headers, and is applied to the externalsurfaces of the semicircular mold. The coolant flowing through nipnozzle assembly is directed generally in a downward directionalong theexternal surface of band 12. Since the upper portions of nozzle 32 and33 of nip nozzle assembly 30 are inserted into annular groove 28 of bandpositioning roller 14a, the flow of coolant in this area will beconfined to annular grooves 28 and 29 of band positioning roller 14auntil itflows out of grooves 28 and 29 to the area 8 between nozzle faceplate and the external surface of band 12 extending downwardly from handpositioning roller l4i. Thus, the directionat which the coolant emergesfrom nozzle openings 36 together with the confining features of annulargrooves 28 and 29 of band positioning roller 14a functioning to prohibitany of the coolant from flowing, splashing, or spraying into the moldcavity defined by peripheral groove 20 of casting wheel 11 and band 12.5

The upper nozzles of nozzles 51 which extend from casting wheel header48 are carefully directed in a downward directionwlthin-casting wheel 11so that the coolant emerging from these nozzles will not flow. splash,or spray into the mold cavity. Furthermore, nozzles 51 are directedagainst the inside wall 52 (FIG. Slot mold ring 19'. and positioningrims l6 and lb function to limit the spray of coolant emerging fromnozzles 51 to the inside external surface of mold ring 19.

Since upper band header 40 is displaced downwardly from nip nozzle 30,there is little. if any hazard of the coolant emerging from the nozzlesof upper band header 40 from coming into contact with the surfnccs'ofthe arcuate mold.

The manual control valves of bypass branch conduit 74, '75, and 76 areregulated so that a relatively low volume and low velocity flow ofcoolant is established from nip nozzle 30. upper band header 40 andcasting wheel header 48, to further reduce any possibility of thecoolant inadvertently splashing or spraying onto the surfaces of thearcuate mold. Check valves '78 and 79 in branch conduits 54 and 55.respectively, and the check valve in valve connection 64 prevent thecoolant from flowing through the entire system from main bypass conduit73 during the preliminary coolant flow. Of course, when the main conduit52 is cut in by main'valve 70, these check valves will open.

When the operator is ready to begin the casting procedure, he rotatesthe casting wheel at a relatively low angular velocity and he adjuststhe metering pin of the pouring pot to create a relatively high rate ofmolten metal flow into the semicircular mold until a pool of moltenmetal is established. it is desirable that the level 26 or the pool ofmolten metal cover the open end of pouring spout 24 so thata minimum ofturbulence is created in the molten metal present in the mold. After theoperator has established the pool of molten metal, main valve of mainconduit 52 is opened by energizing its solenoid, and coolant flows athigher volume and higher velocity through the various branch conduits54-62 to charge nip nozzle assemblies 30 and 44 and headers 40, 41, 42,45, 46, 48, 49, and 50. This results in the coolant already flowing fromnip nozzle 30, upper band header 40 and casting wheel header 40increasing in velocity and volume immediately as the remaining headerscut in. At this point the angular velocity of the casting wheel isincreased to cast the metal in larger volume.

The preliminary cooling during initial casting before the main coolantflow is established allows the operational to begin to bring the castingwheel up to normal speed even before the main coolant flow is applied.Furthermore, there is usually a time delay of approximately 3 secondsbetween the instant when the operator energizes the main valve solenoidand until the full flow of coolant is effected through the variousnozzles of the headers. While this time delay was sometimes critical inthe past with the prior art systems and had to be compensated for inadvance by the operator, it becomes less significant with thepreliminary cooling system disclosed herein since the preliminarycooling system functions to substantially reduce mold deterioration anddestruction to the initial heat transfer in the casting machine.

At this point it should be understood that casting wheel header 48 andupper band header 40 are effective to extend the cooled area of the moldfrom pouring spout 24 and nip nozzle assembly 30 down toward the lowerpart of casting wheel 11 during the preliminary stages of casting, andthe slow angular velocity of the casting wheel during this stage ofcasting allows the heat of the molten metal to dissipate within thislength of casting wheel travel so that the metal is at an acceptabletemperature level which will not damage the materials of the castingmachine. Thus, the hazards of operator error are reduced significantlywithout any detriment to the normal function of the machine.

While the invention has been disclosed as being energized by manuallyoperating the circuits of the valve solenoids, the system lends itselfto an automatic program of operation where the main valve 70 is openedautomatically after the opening of bypass valve 80. For instance,circuitry has been developed to open main valve 70 after a predeterminedtime delay subsequent to the initial opening of bypass valve 80, to openmain valve 70 when the temperature of the casting wheel reaches apredetermined level and to open main valve 70 when a pool of moltenmetal has been detected at the entrance of the arcuate mold by a nuclearmetal level detector. Obviously. combinations of these arrangements, andvarious other automatic control arrangements can be developed.

Circuitry has also been constructed for an automatic start up systemwhere the molten metal flow rate, casting wheel speed and cooling waterare all automatically controlled.

While this invention has been described in detail with particularreference to preferred embodiments thereof, it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinbefore and as defined by theappended claims.

lclaim:

1. In a process for continuously casting metal where metal in a moltenstate is poured from a pouring spout into a semicircular mold formed bya peripheral groove of a rotatable mold ring and a continuous flexibleband, the improvement therein comprising first applying a coolant at arelatively low volume only to the outer surface of the band and theinner surface of the mold ring at the pouring spout and through adownwardly directed arc of the mold from the pouring spout as the moldtemperature increases due to the transfer of heat from the molten metalduring the initial stages of casting to prevent the mold cavity frombeing wet at the introduction of molten metal into the cavity, andsubsequently increasing the volume of flow of the coolant to the samesurface of the band and the mold ring and applying additional volumes ofthe coolant to the other portions of the external surface of the moldring and band as the mold temperature increases after the initial stagesof casting.

2. The invention of claim 1 wherein the step of first applying a coolantat a relatively low volume to portions of the external surfaces of themold includes applying the coolant to the portrons of the externalsurfaces 0 t e mold prior to any increase in mold temperature andcontinuing the low volume application of coolant during the initialstages of casting.

3. The invention of claim 1 wherein the step of first applying coolantcomprises applying coolant through a nip nozzle adjacent the flexibleband at the position where the flexible band first contacts the castingwheel and applying coolant to the flexible band as it passes through thefirst portion of its are of movement with the casting wheel.

4. The invention of claim 1 wherein the step of applying additionalvolumes of the coolant comprises applying the coolant to the sidesurfaces of the casting wheel.

1. In a process for continuously casting metal where metal in a moltenstate is poured from a pouring spout into a semicircular mold formed bya peripheral groove of a rotatable mold ring and a continuous flexibleband, the improvement therein comprising first applying a coolant at arelatively low volume only to the outer surface of the band and theinner surface of the mold ring at the pouring spout and through adownwardly directed arc of the mold from the pouring spout as the moldtemperature increases due to the transfer of heat from the molten metalduring the initial stages of casting to prevent the mold cavity frombeing wet at the introduction of molten metal into the cavity, andsubsequently increasing the volume of flow of the coolant to the samesurface of the band and the mold ring and applying additional volumes ofthe coolant to the other portions of the external surface of the moldring and band as the mold temperature increases after the initial stagesof casting.
 2. The invention of claim 1 wherein the step of firstapplying a coolant at a relatively low volume to portions of theexternal surfaces of the mold includes applying the coolant to theportions of the external surfaces of the mold prior to any increase inmold temperature and continuing the low volume application of coolantduring the initial stages of casting.
 3. The invention of claim 1wherein the step of first applying coolant comprises applying coolantthrough a nip nozzle adjacent the flexible band at the position wherethe flexible band first contacts the casting wheel and applying coolantto the flexible band as it passes through the first portion of its arcof movement with the casting wheel.
 4. The invention of claim 1 whereinthe step of applying additional volumes of the coolant comprisesapplying the coolant to the side surfaces of the casting wheel.